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How much "in the hole" (piston @ TDC)

Started by Pop-pop2, April 06, 2019, 03:56:37 PM

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kd

April 11, 2019, 07:29:45 AM #25 Last Edit: April 11, 2019, 09:10:43 AM by kd
I'm with PoorUB.  It makes sense to take advantage of the fact the barrels are available to be machined before assembly.  I don't think I could ignore the opportunity to fine tune that part of the assembly.  You haven't said if both decks are the same.  I would confirm what both barrels need and have them tuned up.  It will also clean up the surfaces if done properly.   

If you decide you do want to leave them you have other options. For example, a .027 Cometic head gasket (available) will cut the squish a little more down to .034.  If the engine has base gaskets instead of o-rings, they can be adjusted with the right thickness size base gasket.   As said, checking the valve pocket clearance will be important no matter which way you go.

added later;

The TTS tuner (if done on a dyno properly) will tune each cylinder on it's own merit so the tune should be OK.  Any off balance in compression will have to be kept in mind if doing a compression check at some time in the future so it doesn't get interpreted as an engine defect. Check it after assembly and break in and record it so you know.   It shouldn't IMO cause a vibration from off balance cylinders that can be felt but it will likely have a very slight effect on the toque and power.
KD

PoorUB

It will tune just fine, it will run just fine. You might give up a couple HP.
I am an adult?? When did that happen, and how do I make it stop?!

rigidthumper

That huge hemi combustion chamber has no quench area with that piston, so that .007" is not a big enough issue to worry about. 
I think  @ 10.25, with a 35° close cam, you're gonna need a decent tune.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Pop-pop2

Thank you all very much.

P.S. Yes, it does have manual compression releases.

Hilly13

Pop you got a good tuning device, if you get it dynoed by a competent tuner that likes TTS they will get it running right for you, would you post a sheet if you go that way?
Just because its said don't make it so

Pop-pop2

Yes, but it may be awhile,  I go in for surgery in May.

Hilly13

Just because its said don't make it so